Dipper-latch actuator



May 7, 1929. w. M. HOUGHTON DIPPER LATCH ACTUATOR Filed July 2, 1927 3 Sheets-Sheet May 7, 1929. M. HOUGHTON v 1,712,040

D'I'PPER LATCH ACTUATOR Filed July 1927 3 Sheets-Sheet 2 ,5 or/zeys' o-M M'm latented May 7, 1929.

WILLIAM M. HUUGHTON, OF NEWTON, MASSAGHITSETTS.

DIPPER-LATCH ACTUATOR.

Application filed July 2, 1927. Serial No. 203,104.

This invention pertains to power shovels or the like of'that kind in which the dipper of the apparatus is provided with a movable closure or door which is normally held closed by a latch, the present invention relatingmore particularly to means for releasing the latch so as to permit the door to open and release the contents of the dipper. I

As usually constructed the latch is a sliding bar carried by the movable door of the dipper and normally engaging a'keeper on the dipper body. When so constructed the latch sustains a substantial part of the weight of the contents of the filled dipper and considerable force (of the order of 1000 lbs. per cubic yard of dipper size) is required to withdraw the latch from the keeper. Owing to the difiiculty of this operation it is frequentlynecessary for the shovel operator to use both hands in pulling the rope or other device for retracting the latch, thus obliging him to release his grip on the shovel operating levers. vIn some instances the operation of the latch pull rope is delegated to a helperv but either mode of operation is wasteful of time and unsatisfactory. To avoid this difficulty certain attempts have been made to provide power means forreleasing the latch for example, small electric motors or power actuated clutch drives); but these arrangements have been expensive, relatively slow in action, and not wholly dependable.

In accordance with the present invention I have devised a latch actuator which withdraws the latch instantaneously by the release of stored up energy (such for example as that supplied by a stressed spring). Release of this energy may beaccomplished with but slight effort on the partof the shovel operator and a new supply of energy is automatically stored up by the opening of the door or bottom member of the dipper, while the operative parts are so-disposed or protected that they are not readily injured.

lo the accompanying drawings I have illustrated certain embodiments by way of example and in the drawings Fig. 1 is a diagrammatic side elevation of a complete power shovel of usual type, but embodying the present invention;

2 is a fragmentary side elevation. to large scale, showing the rear part'of the dipper body and a portion of the handle, together with one form of my improved latch actuating means, the door or closure member of the dipper being in normal closed position;

Fig. 3 is a View similar to Fig. 2 but showing the door of the dipper in its open position I Fig. 4 is a fragmentary plan view, partly in section, showing certain details of a releas on the line 88 of Fig. 2.

Referring to the drawings the numeral 1 designates a shovel apparatus or excavator of substantiallyusual construction compris- Fig. 8 is a vertical section, to smallerscale,

ing a revolving platform rotatably mounted upon a suitable base, such for example as the caterpillar tractor 2. The apparatus comprises the boom tcarrying the dipper handle 5 which supports the dipper 6 at its outer end. This dipper may be of any usual shape and is furnished with a movable closure or door 7. This door preferably comprises a pair of spaced hinge members 8 and 9 respectively (see Fig. 6);which are curved rearwardly and upwardlyand pivotally connected at 10 to the body of the dipper. The rear side of the door or closure 7'3is furnished with suitable guides for a sliding latch bar 11 having a beveled forward end 12 adapted to engage a keeper 13 carried by the dipper body, all in usual manner.

In accordance with the construction shown.

in Figs. 2, 3 and 4 I mount a rock shaft 14 in suitable bearings carried by the forward end of the dipper handle 5 and on this shaft I mount a. lever device here shown as having a short lever arm 15 and a long lever arm 16. I secure a spring housing 17 to the handle, such housing enclosing one or more springs 18, here shown as of coiled compression type, which rest upon the lower end of the housing and whose upper ends bear against a collar 19 fixed to a rod 20 whose lower end is pivotally attached at 21 to the short lever arm '15.

I also mount upon the forward end of the dipper handle a releasable catch member, here shown as a bell-crank lever pivoted at 22 and having the arm 23 provided at its forward end with a roller 24 constituting the catch proper and which is adapted normally to en gage the upper part of the long lever arm 16,

thus keeping the latter in the full line position shown in Fig. 2 with the springs 18 under compression. Preferably the free end of the long lever arm 16 is beveled as indicated at 25 to facilitate its reengagement with the catch roller 24-. In orderto protect the arm 16 and to keep it in proper relation to other parts, 1 preferably confine it between P211121]..- lel guides 26.

The bell-crank catch lever also comprises an arm 27 to which one end ot a suitable actuatingelement28 is attached. This actuating elementina be a light cord leading down into the operators cab, or it may, it de sired, be connected to a solenoid or equivalent device'ztor moving the catch electrically. ln order to maintain the catch lever inoperative position, except when released by actuation of member 28, I provide a tension spring 29 secured at one end to the arm 2-? and at its other end to a convenient lined part.

irbout the shaft ll Iwrap a flexible connection 31., for example a chain whose other end connected to the latch '11. This chain permits die latch to reengage its keeper while the lever device occupies the position shown in Fig. 2. Although I may wind the chain 31 about shaft ll as described, I may, it desired, connect the end of the chain to arm carried by the shaft l-i, for example the arm 15, and the shaft-may be considered as the emaivalent of a lever in its operation in releasing the latch.

lhc long arm 16 of the lever device is con nected to the dinper door, preferably by n'ieans of a pair or tClOH-L'OPlllg links. One link is pivotally secured to the dipper door at the point- 32, such link having an abutment shoulder This link telescopes within the tubular link which connected to the long lever arm 1-6 at the free end 31' of the lllll constitutes a second abutmentcngageable with the almtment ill hereinafter described for moving the lever arm 16 in oppos tion to the spring 18. I

lin'norm-al position, that is to say, when the dipper door is closed, the latch actuating mechanism occupies the position shown in Fig. 2, it being assumed that the dipper has been actuated to dig up a load of material and that such material is resting upon the door oi the dipper. The door may be opened to discharge this lead by a slight pull upon the cord 28. The catch roller may be mored quite easily so as to d k om the lever arm 16 and thereupon. tne spring 155 is free to expand, thus driving the collar 19 and rod 20 upwardly and rocki the shaftl l in a clockwise diectien. 'lhs winds up chain 31 and almost instantly pulls the latch 11 out of engagement' with its keeper, thus permitting the door to open under the weight of the contents of the dipper..

' Inthenormalpositionof the parts, as shown in Fig. 2, the end 37 of the tubular link 35 is spaced from the abutment 34 ot' the link 83 so that when the lever is released from its catch, it is free to swing down to the dotted line 16 of Fig. 2. At the end of this movement the end 37 of the link 35 is substantially in contact with the abutment 34c, and as the door begins to swing open under the weight of the load, the abutment El pushes the link 35 to the left, as viewed in F 3, thus compressing the spring 18 with a constantly increasing leverage due to the approach of the pivot 32 to the line defined by the pivots 10 and 86. As the door advances toward its fully opened position, the lever 16 assumes first the position 16 of Fig. 3, where the beveled end 25 engages the roll 2t,

-causing the latter to ride up over the beveled surface 25 until the long lever arm 16 escapes from beneath the roll as shown in Fig. 3. The door may continue to open beyond this point, but due to the continued approach of the pivot 32 toward the line delin ed by the pivots 10 and 36 the corresponding movement of lever 16 grows less and less and although the long lever arm may reach some such position as 16 the over travel is short. By properly proportioning the parts, the latch may be reset at almost any desired door opening. lVhen the door again closes the long lever arm 16 returns to the position 16 where it is stopped by the catch roll 24. The spring 18 is compressed during the above operation so that the parts are restored to the position shown in Fig. 2. The door is free to close and its closing may be accomplished in any usual manner, as for example by gravity, and

when the door closes the abutment member 3 1- recedes from the link and at the same time the latch 11 snaps into engagement with its keeper 13, the chain 31 slacking and permitting this movement of the latch.

Thus as above described the large amount of stored up energy furnished by the spring 18 and which is suiiicicnt to withdraw the latch, is readily released by a sligl'rt pull on cord 28, while the action of the door in opening restores the spring to its normal stressed condition ready for thenext subsequent operation. If tor any reason the initial opening of the door should not be enough to reset the spring, a slight shaking of the dipper, as is common for detaching sticky material, will swing the door sutiiciently to reset the spring. It may be noted in this connection that the spring may act tosome extent at least as a shock absorber to prevent too rapid opening of the door.

Referring to 5 and 6 l have shown a modified arrangement in which the dipper door is provided with a pivot 40 forming a fulcrum for a lever comp 'ising the long arm 41 and toe relatively short arm 42. The long arm 41 is provided at its end with recess for engagement with. a catch roll l4: mountec lit) prises an arm which is pivotally connected.

to the link 51 whose other end is pivotally connected to the dipper body at'52. A heavy leaf spring 53 is mounted upon the dipper door and one end of this sprlng is connected by means of a link54 to the short lever arm 42.

In this arrangement the end otthe lever arm 41 normally engages the catch roller'44, the spring 53 being under stress and the end 42 of the arm 42being disposed adjacent to the lettdiand end of the slot in the link 47 as viewed in Fig. 5. The arm 4lot'the lever passes through an elongateopening 11. in the latch 11 and when the catch roll 44 is released from the recess 43 of the lever arm 41, the

spring 53, acting through link 54, suddenly swings lever arm 41 in a clockwise direction, as viewed in Fig. 6, thus withdrawing the latch 11 from its keeper andmoving the end 42 of the lever arm 41 to therighthand end of the slot 47. hen the dipper door swings to open position, the fulcrum 49 is moved relatively to the pivot point 52, thus changing the arrangement of the link and lever connections and exerting a powerful pull upon the end 42 of the lever arm 42, thus again placing the spring 53 under stress. The leverage increases as the spring is compressed and when the arm 43 passes the roller 44, it is reengaged by the latter, thus retaining the parts in normal position. By reason of the elongate slot 11 in the latch, the latch is now free to ride over its keeper thus again locking the door of the dipper in closed position.

In Fig. 7 I have illustrated a slight modii'icat-ion ot the last-described arrangement, in which I substitute a coiled spring for the leaf spring 53. This coiled spring 55 is mounted in a suitable housing 55 on the door of the dipper, and one end ot this spring engages a collar 5'? on a rod 58 pivotally secured at 59 to the arm 42 ot the lever. This spring 55 operates in the same way as the spring 53 and. need not be further described.

In the arrangement shown in Figs. 2 and 3 the latch actuating parts are mounted upon the shovel handle. while in the construction shown in Figs. 5, 6 and 7, the latch controlling parts are at the upper end of the door. Thus in the several forms of the apparatus, the moving parts are practically safe from injury in the normal operation of the shovel.

Moreover, the parts are simple, rugged, and durable and of a character such that they are not readily disturbed or injured, although, as above described, the release of the latch. is quickly andeasily accomplished by a slight pull on a light cord, so that the shovel operator may dump the dipper by the use of one hand. p

While I have shown and described certain desirable arrangements providing the desired energy for releasing the latch instantly and for restoring this energy by the action, of

the weight of the dipper door or its contents, I wishit to be understood that the arrangements here shown are merely by way of example and are not to be considered as restricting or defining the invention but that other and equivalent means and arrangements of parts may be employed within the scope of the appended claims.

I claim: e i

1. Apparatus of the class described comprising a dipper having a movable closure, retaining means normally holding the closure in closed position, meansconstituting asource of energy built up by the movement of the closure for rendering the closure retaining means'inoperative, and means normally preventing release of said energy.

2. In combination with a dipper of the class described having a movable closure, retaining means for keeping said closure shut, and

spring means set by the closure for releasing the retaining meansto allow the closure to open.

3. In combination with adipper of the class described having a movable closure and a latch for keeping said closure shut, spring means set by the closure for retracting the latch to allow the closure to open, means for transmitting movement of the spring means to the latch, and releasable means normally restraining the spring means trom acting.

4. Apparatus of the class described comprising a dipper having a hinged door, a sliding latch normally retaining said door in closed position, a spring set by the door constituting a source of stored-up energy for moving the latch to inoperative position, and

releasablemeans normally preventing the spring from acting.

5. In combination with a dipper ot the class described having a door and locking means tor the door comprising a latch and a keeper therefor, means set by the door for withdrawing the latch from the keeper to permit the door to open, said means comprising a spring actuated element, connections between said element and the latch, and releasable means normally preventing said spring actuated element from withdrawing the latch.

6. In combination with a dipper of: the class described having a movable closure and retaining means for keeping said closure shut, spring means-tor retracting the retainlOO ing means to allow the closure to open, means for transmitting movement from the spring means to the retaining means, said transmitting means comprising a lever having a relatively short arm connected to the spring means, and a releasable catch device normally engagin a relatively long arm of the lever.

7. Apparatus oi the class described comprising a dipper having a movable closure, ret-a rng means normally positioned to hold said closure closed, a source oi stored-up energy for moving the retaining means from normal position to permit the closure to open, means for rele sing said energy, andineans actuated by the load in the dipper "for restoring said cncrg 8. Apparatus the class described comprising a dipper having a movable closure, a latch normally positioned to keep the closure closed, a source of stored-up energy for retracting the latch, means for releasing said energy, and means actuated by opening of the closure for restoring said energy.

9. Apparatus of the class described comprising a dipper having a swinging closure, a movable latch normally retaining the closure in closed position, a source or" stored up energy for retracting the latch, means for releasing said energy, and means actuated by the closur as it swings open for restoring said energy- 10. in combination with a dipper of the class described having a movable closure and a latch for keeping saidc'losure shut, a spring constituting a source of stored-up energy for retracting the latch to allow the closure to o pen, means for transmitting movement from the spring to the latch, a releasable catch normally restraining the spring, and means for trai'ismittiug movement from the closure, as it opens, to the spring for restoring the latter to normal position after it has been re leased by operation of the catch.

ll. In combination with a receptacle having a movable bolt carried by the closure and a keeper on tiie -receptacle with which the bolt positively engages to lock the closure shut, a source of stored-up energy for with drawing the bolt from the keeper to permit the closure to open, and means actuated by the closure, in opening, for restoring said energy.

12; ln combination ith a dipper of the class described having a ooor, and locking means for the door conu rifng a latch and a keeper therefor, a lever for withdrawing the latch from the keeper, connections between. the lever and latch, a normally stressed spring tending to move the lever to withdraw the latch trom the keeper, a releasable catch for the lever, and connections between the door and lever so constructed and arranged that when the door opens it moves the lever in a direction such as to stress the spring.

18. In combination with a dipper of the class described having a movable closure, and a latch for keeping said closure shut, a spring for retracting the latch to allow the closure to open, means for transmitting movement from the spring to the latch, said transmitting means comprising a lever, a releasable retainer normally engaging the lever and thereby preventing the spring from acting, and means for transmitting movement from the closure to said lever.

14-. In combination with a dipper ol the class described having adoor, and latch normally holding the door closed, means for "ithdrawing the latch to permit the door to open, said means comprising a lever, a spring normally tending to move the lever to withdraw the latch, a releasable catch normally preventing movement of the lever by the spring, means :tor releasing the catch to per mit the spring to withdraw the latch and al lowthe door to open, and connections between the door and lover such that when the door opens the lever is restored to normal position engaging the catch.

15. In combination with a dipper of the class described having a door and locking means for the door c-om firising a latch and a keeper therefor, means con'iprising a'lever for withdrawing the latch from the keeper, a normally comp: ssed spring tending to move the lever and withdraw the latch from the keeper, a catch normally engaging the lever to prevent its movement, means for moving the catch to release the lever thereby permitting the spring-to expand and withdraw the latch to allow the door to open, and means actuated by the door as it opens for restoring the lever to normal position and for recompressing the spri' Q 16. in combination with a dipper of the class cescribed having a door and locking means for the door comprising a latch and a keeper therefor, a lever for withdrawing the latch from the keeper, connections between the lever and latch, a normally stressed spring constituting a source of stored-up energy for actuating the lever to withdraw the latch from the keeper, a catch normally preventing movement of the lever, means for releasing the catch to permit the spring to move the lever and withdraw the latch to allow the door to open, and connections for transmitting movement from the door to the lever for rcstressing the spring.

17. In combination with a dipper of the class described having door and lockin means for the door comprising a latch and a keeper therefor, a lever for withdrawing the latch from the keeper, connections between the lever and latch, a normally stressed spring constituting a source of stored-up energy for actuating the lever to withdraw the latch from the keeper, a catch normally preventing movement of the lever, means for releasing the catch to permit the spring to move the lover and Withdraw the latch to allow the door to open, and means transmit ting movement from the door to the lever for re-engaging the lever with its catch and for restressing the spring.

18. In combination With a dipper of the ly preventing movement of the lever, means for releasing the catch to permit the spring to move the lever and Withdraw the latch to allow the door to open, and connections comprising relatively movable abutment elements for transmitting movement from the door to the lever for re-engaging the lever With its catch and for restressing'the spring.

19. In combination With a receptacle having a closure and locking means for the closure comprising a latch and a keeper therefor, a lever device comprising a short arm and a long arm, a spring connected to the short arm, a releasable catch normally engaging the long-arm and thereby keeping the spring under stress, means for transmitting movement of the lever device to the latch for Withdrawing the latter from its keeper to permit the closure to open, and lost motion connections between the closure and the long arm of the lever device.

20. In combination with a dipper of the class described having a handle, a hinged door, and locking means for the door comprising a latch and a keeper therefor, a rockshatt mounted on the handle, a long lever arm and a short lever arm fixed to the shaft, a chain Wrapped about the shaft and connected to the latch, a spring connected to theshort lever arm, aid spring norm ally being stressed and tending to swing the arm and rock the shaft thereby to Withdraw the latch from the keeper, a catch normally engaging the long lever arm to prevent the spring from rocking the shaft, means for releasing the catch from the arm, and telescoping links pivotally connected to the long lever arm and to the door, respectively, said links permitting movement oi thelong lever arm When released by the catch but transmitting movement from the opening door to the long lever arm for returning the latter to its normal position. Q

21. In combination with a dipper of the class described having a handle and a hinged door and locking means for the door comprising a latch and a keeper therefor, a rockshaft mounted on the handle, a long lever arm and a short lever arm fixed to the shaft, a chain transmitting movement lfrom the shalt to the latch, a spring connected to the short.lever arm, said spring normally being stressed and tending to swing the arm and rock the shaft thereby to Withdraw the latch from the keeper, a bell-crank lever havinga roller on one arm normally engaging the long lever arm to prevent the spring from rocking the shaft, means for turning the bellcrank lever to disengage the roller from the long lever arm, and a pair of links having abutment elements, one link being pivotally connected to the door and the other to the long lever arm, the abutment elements of said links normally being separated to permit the long lever arm to move when disengaged by the roller but engaging as the door opens and thereby returning the long lever arm to normal position.

22. In combination with a dipper of the class described having a movable closure, and a latch for keeping-said closure shut, a spring for retracting the latch to allow the closure to open, means for transmitting movement from the spring to the latch, said transmitting means comprising a rocking member, a

releasable retainer normally engaging the rocking member and thereby preventing the spring from acting, and means for transmitting n'ioven'ient from the closure to said rocking member,

Signed by me at Boston, Massachusetts, this 25th day of June, 1927.

WILLIAM M. I-IOUGHTON. 

